Refrigerating machine



H. NIELSEN REFRIGERATING MACHINE Dec. 11, 1928.

Filed March 19, 1927 ATTORNEY Patent Dec. 11, 1928.

team? HOLGER NIELSEN, 0F BUFFALO, NEW YORK.

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Application filed March 19, 1927. Serial No. 176,775.

In refrigerating machines where the-compressor is to receive or suck gas from two or more evaporators with different temperatures and corresponding different back pressures, it is at present customary to have hand operated valves by which the compressor can be connected to any evaporator in which the back pressure has increased over the desired figure. v

The present invention has for its object to automatically connect to the compressor any of the nipes Am B. Memb I est back her D is-loaded by a spring E. The force of of two ormore evaporators thatmay need most to be sucked from. Say for instance that the back pressure in two'evaporators is desired to be kept at 20 and 30 pounds per square inch, having a normal difference of IQ pounds per square inch, and say that this difference has increased to 12 pounds per square inch, then the compressor should be connected to the evaporator with highest pressure so as to bring this down to only 10 pounds per square inch over the pressure in the other evaporator.

If, on the other hand, the difference is only 8 pounds per square inch, then the compressor should be connected to' the evaporator with lowest pressure so as to bring this farther down and make the desired difference of 10 pounds per square inch.

These operations are done automatically in the device in question in whichthe variation of pressure difl'erence is used for operating an opening and closing device for the pipe line branching off from? the compressor suction line to two different evaporators.

The device is shown in the accompanying drawing, in which Fig. 1 is a vertical section, and

Fig. 2 is a horizontal section.

Z is a body from which pipe C leads to the compressor suction side. Pipe A leads to evaporator with highest pressure, and pipe B leads to the evaporator with lowest pressure. D is a movablemember that can close either er D is exposed to highest back pressure from below and lowpressure from above; further, memof this spring corresponds to the desired difference in back pressure. If this difference increases over that corresponding to load of spring, then member D goes up and closes the pipe to low pressure evaporator, allowing compressor to suck down the pressure in high pressure evaporator.

If, 011 the other hand, the difference in pressure is less than that corresponding to load of spring, then member D goes down and allows the compressor to suck the pressure in low pressure evaporator farther down. Thus the difference of pressure in evaporators will be kept constant continuously as long as the compressor runs.

- In cases Where more than two different pressures are desired, either or both of the two pipes A and C can-be connected to another device of two pipes will then branch 011' to other evaporators, etc., thus giving possibility of keeping four or even more back pressure at constant differences. l

Having now particularly described and as certained the nature of my invention and in what manner the same is to be performed, I declare that what I claim is:

In a refrigerating apparatus a coupling member connecting three pipes, one leading to the suction side of a compressor, one leading to a low pressure evaporatorand one leading to a high pressure evaporator, and valve means in said member for maintaining a predetermined pressure difference. between the two evaporators, said means closing said pipe leading to the evaporators when the otheriis closed by said valve means. 7 I

- leading to the high pressure evaporator when I the pressure difference between the two evapo- HOLGERQIIELSEN. 

